A computer program for on-line measurement, storage, analysis and retrieval of urodynamic data

A computer program is presented which allows for direct connection of a minicomputer to a urodynamic set-up. The program stores measured pressure and flow data in a random access disc file with minimal intervention of the urodynamicist, and enables the direct application of a number of methods of analysis to the data. The program is modular, and other analysis methods are easily added. Results of analyses are stored in the same disc file, and both results and measured data can be quickly and easily retrieved. The program is written in FORTRAN; hardware-dependent functions (analog input, graphics display, and random access disc storage) are implemented in subroutines (partly assembler) which can easily be replaced

In vitro comparison of isometric and stop-test contractility parameters for the urinary bladder

Contractility parameters in the urinary bladder can be calculated from isometric contractions (no extra patient load as compared to routine cystometry) or from stop-tests (more accurate, simpler analysis). A stop-test involves a voluntarily interrupted micturition with pressure and flow measurement. In a series of measurements in vitro on pig urinary bladder strips, parameters of the first type, obtained either by analyzing isometric contractions in terms of the Hill model, or by making phase plots, were compared to parameters of the second type. A good correlation was found. Th parameter correlating best with the maximal contraction velocity of the bladder, normalized for differences in initial muscle length, as obtained from stop-test, is the isometric contraction force, which can be obtained from an isometric contraction by either of the two analysis techniques. Clinically, making phase plots seems more promising than analyzing contractions in terms of the Hill model

Estimation of the maximum contraction velocity of the urinary bladder from pressure and flow throughout micturition.

The contractility of the urinary bladder can be adequately described in terms of the parameters P0 (isometric pressure) and Vmax (maximum contraction velocity). In about 12% of urodynamic evaluations of patients these clinically relevant parameters can be calculated from pressure and flow rate as measured during micturition. A method was developed of estimating Vmax for any micturition from these signals. The properties of this estimated contractility parameter were clinically tested and are discussed

Urodynamica ? Urodynamica !

In een van de eerste voorstellingen van Neerlands Hoop in Bange Dagen begon Freek de Jonge een item met de opmerking: “De mensen vragen mij wel eens: “maken jullie wel eens iets mee?”” Hij vertelde dan verder dat zij nooit iets meemaakten, en gaf daar een voorbeeld van. Aan mij daarentegen wordt zelden of nooit gevraagd of ik wel eens iets meemaak. Wel wordt mij regelmatig gevraagd wat voor werk ik doe, waarop ik dan “wetenschappelijk onderzoek” antwoord. Daarop wordt meestal een nadere uitleg gevraagd, een enkele keer letterlijk in de vorm: “En wat doe je dan zo de hele dag ?”. Nadat ik geprobeerd heb dat duidelijk, maar toch kort uit te leggen, want een zap-moment is altijd nabij, volgt soms nog een vraag, ingegeven door mijn vermelding dat ik dit al 34 jaar doe, namelijk: “En hoe kun je daar dan zolang mee bezig zijn ?” In deze rede zal ik proberen aan de hand van een aantal voorbeelden die twee vragen te beantwoorden. Als dat lijkt op een verantwoording, dan ligt dat in de lijn van het motto van mijn proefschrift uit 1977, dat luidde: “dit proefschrift is opgedragen aan het Nederlandse Volk, dat ervoor betaalde” |1. Zo’n verantwoording hoeft gelukkig niet saai te zijn: we zullen in vogelvlucht zien hoe een fysicus het urinewegensysteem beschouwt, en voorbeelden van fysische onderzoek aan de urinewegen, en we zullen ook wat uitstapjes maken om in korte intermezzi aspecten van het wetenschappelijk onderzoekbedrijf te bekijken die bijdragen aan het beantwoorden van de gestelde vragen.Rede, in verkorte vorm uitgesproken bij de aanvaarding van het ambt van bijzonder hoogleraar in de Fysica van de Urinewegen aan het Erasmus MC, faculteit van de Erasmus Universiteit Rotterdam, op 6 juni 200

Bolus propagation in pig ureter in vitro

Pig ureters were made to propagate injected fluid boluses by electrical stimulation in vitro. The propagation velocity was determined from EMG measurements made at several points along the ureter. It was found that this velocity varied both along the ureter and as a function of time, and that it was related to the contraction pressure but not to the bolus size

Analysis of pressure-flow data in terms of computer-derived urethral resistance parameters

The simultaneous measurement of detrusor pressure and flow rate during voiding is at present the only way to measure or grade infravesical obstruction objectively. Numerous methods have been introduced to analyze the resulting data. These methods differ in aim (measurement of urethral resistance and/or diagnosis of obstruction), method (manual versus computerized data processing), theory or model used, and resolution (continuously variable parameters or a limited number of classes, the so-called monogram). In this paper, some aspects of these fundamental differences are discussed and illustrated. Subsequently, the properties and clinical performance of two computer-based methods for deriving continuous urethral resistance parameters are treated

Efficient storage of urodynamic signals by computer: application of FAN adaptive sampling

Digital storage of urodynamic signals such as detrusor pressure and flowrate at a sufficiently high sampling rate (10 samples per second) to allow subsequent analysis requires considerable computer memory. A procedure for compressing these data by deleting redundant samples (the fan method of adaptive sampling) was tested. The method allows a flexible adaptation to specific hardware and a compromise between storage requirements and accuracy. In this study the number of samples required for adequate reconstruction of the detrusor pressure signal could be varied from 80% to 4% of the original number of samples by varying the average difference between reconstructed and original signal from 0.01 to 2 cm H2O. Fast components of the measurements (for example cough peaks) which were lost if a lower sampling rate or averaging was used to obtain equally low storage requirements were unaffected by this compression technique